[refactor] engines: use datetime.fromisoformat instead of datetime.strptime where possible (#6394)

Refactor engines that parse ISO 8601 dates with strptime to use
fromisoformat instead. In most cases this is a direct replacement of
strptime(text, "format") with fromisoformat(text).

For engines where the source has a trailing "Z" that strptime consumed
as a literal (e.g. "%Y-%m-%dT%H:%M:%S.%fZ" in huggingface.py), add
rstrip("Z") to keep the output naive and preserve the existing behavior.

In sogou.py the date is extracted with a regular expression, which can
yield strings like "2026-7-11". strptime accepts this via its format
string, but fromisoformat does not. To preserve the existing behavior
and satisfy the format fromisoformat expects, add zero-padding for the
month and day.

Closes: #6098
---------
Signed-off-by: OneVth <onebrotravel@gmail.com>

searx/engines/rumble.py

@@ -58,7 +58,7 @@ def response(resp):
         title = extract_text(result_dom.xpath(title_xpath))
         p_date = extract_text(result_dom.xpath(published_date))
         # fix offset date for line 644 webapp.py check
-        fixed_date = datetime.strptime(p_date, '%Y-%m-%dT%H:%M:%S%z')
+        fixed_date = datetime.fromisoformat(p_date)
         earned = extract_text(result_dom.xpath(earned_xpath))
         views = extract_text(result_dom.xpath(views_xpath))
         rumbles = extract_text(result_dom.xpath(rumbles_xpath))